Checkmate
by SpellCleaver
Summary: Cassian is the illegitimate son of the High Lord of the Night Court, so he's told it's an honour when he's betrothed to the Crown Princess of the neighbouring country. But problems like language barriers, diplomatic insults and bad dancing lead to him wondering if this engagement is such a good idea after all. Nessian Oneshot. Fantasy AU/AH


**This idea came to me, and I just ran with it. I recently began to really like Nessian, so here's one of my first oneshots for it. Sorry if the writing seems kind of broken in places.**

 **The bit in the middle with Nesta and Feyre was put in just because those two are my BROTP and I love writing them when they're getting along.**

 **I know that the Archerons don't come from Scythia, but technically the land south of Prythian doesn't have a name, so I just called it that since there are no other human territories with names.**

 **Just to be clear, this is a Fantasy AU, but everyone is human, and no one has magic.**

 **Disclaimer: I don't own ACOTAR.**

* * *

As an illegitimate son of the High Lord of the Night Court, Cassian was told by both his father and his stepmother that it was an honour for their bid to betroth him to the heiress of the neighbouring country to be accepted.

Scythia was on the other side of the mountain range that flanked the eastern side of Prythian, but the Illyrian Mountains had conditions that were too harsh for open trade and travel routes to have been established until the completion of the single road that had recently been built. Before the road, few people had traversed between the two countries, so they'd existed side by side in a state that wasn't quite harmonious, but more akin to completely ignoring each other.

But Cassian's stepmother had come from a village in the range, and when his father had met and married her, the High Lord had gained an interest in the Illyrian Mountains, and what lay on the other side of them. So emissaries were sent, links were established, and a road was built.

And when Cassian came of an age where he was more of a blight of shame on the court than a cute pet for the nobles to coo over, the High Lord set about marrying him off to that country as well.

Cassian's mother had reportedly been a laundress from the Illyrian Mountains as well, and he'd always been curious about them, but that didn't mean he wanted to go further. That didn't mean he wanted to be the Prince Consort in a foreign land, and possibly never see his half-brothers again.

"Why me?" Cassian had asked of them once when they were out of a hunting trip, just the three of them. "Why would a Crown Princess want to marry a bastard from a country she's never seen?"

Azriel - also a bastard of the High Lord, and one who'd suffered greatly for that fact - had just tightened his scarred hands on his horse's reins and hadn't answered. Rhys, the only legitimate heir their father had, after their sister had died in an assassination by the Spring Court aged five, had said in his place, "I've heard that Nesta Archeron is a domineering woman, and will likely be a powerful queen. They were probably hoping for a consort who wouldn't interfere much, or be puffed up on his own blood status and wealth."

"Like yourself?" Cassian had teased in response, hoping the banter would hide how disgusted he felt at the whole thing. Rhys just grinned, conceding the point.

"She hasn't technically chosen yet, though," Azriel informed them quietly. No one asked how he knew; he always just _knew_. "That's why she's coming to Prythian in a few weeks; to make her decision."

Rhysand had raised an eyebrow at that, and Cassian had drawled, "So I just have to be my charming self, and only then might I be of worth to our lovely father?" Azriel grimaced at the truth of the statement, and Rhys didn't defend the High Lord. His brother would go to his death defending his mother, the Lady, against horrible rumours, but he'd given up on trying to convince himself their father was good a long time ago. Cassian clicked his tongue. "Wonderful."

The official announcement had happened at dinner that night, and until today the palace had been awash with panic and preparations as they scrambled to be ready in time. Apparently, it wasn't just the Archeron family that would be visiting the Night Court that week - this was the first contact made between Scythia and Prythian for as long as living memory held, and representatives from all the courts would be attending.

Including, to Rhys's utter chagrin, the heir to the Spring Court.

Apparently being at political war with a territory - having been at it for _years_ \- didn't stop it from being a grave offence to refuse to invite them to such a monumental event.

Even when the animosity between the heirs was absolutely legendary. Even when the last time they'd met, it'd ended it several broken limbs.

But thankfully, the entourage that the Archerons arrived in came before any of the other High Lords, save the young Helion Spell-Cleaver, arrived. It was an upside in a situation that quickly turned problematic.

The Archerons spoke a completely different language to them.

It'd dawned on Cassian when he first met them at the gates to the palace, and Princess Nesta looked down at him from her seat on the back of a large horse. She opened her mouth to say something, when a wisp of playful chatter drifted forward from towards the back of the party. He tensed when he realised he didn't understand the words, and that they sounded very different to his own language.

Nesta gave him a polite, frigid smile, then gestured for him to lead the way. She didn't say anything.

They'd made it to the throne room before she did. The High Lord smiled welcomingly at her - or at least tried to. The Lady looked much more relaxed and interested in the entourage, so it was to her that the princess addressed her greeting. On Nesta's right stood a younger woman, and they looked so similar Cassian had to assume they were sisters.

Because he knew where to look, Cassian saw the momentary shock and panic that enveloped his father's face when Nesta greeted them in her own language, but it was gone in an instant. But everyone breathed a sigh of relief when Nesta spoke in what they'd all assumed was the common tongue.

"It is a honour to be here, your liege," she said, her dialect slightly broken, but passable. "I am the Princess Nesta Archeron of Scythia, and this is my sister, Feyre." The woman beside her bowed her head, then looked up again. It was her that spoke next.

"We look forward to spending time with you, and are sure we shall enjoy our stay here," she said, donning a pretty smile.

"You speak with the intonations of a commoner," Keir, the steward of the Hewn City, observed from his place standing by the High Lord's throne. He'd spoken out of turn, and Cassian saw the High Lord clench his fists and hiss something, but Cassian was more interested in how the sisters reacted.

It was obvious that Nesta didn't understand what had been said, but the tone of the sentence was unmistakably derogatory. She narrowed her eyes at the steward. She said something to her sister in Scythian, who responded the same. The tension in the room was palpable as the two conversed.

The Crown Princess frowned deeply at whatever Feyre had said, and glared at Keir with such fire and hatred that it was a wonder he didn't combust on the spot. She spat something else in Scythian. The High Lord shifted uncomfortably in his seat at the way things were going.

Feyre just gave Keir a saccharine smile. "That's probably because I was taught by a commoner - my old nursemaid. However, my sister says it's outrageously hypocritical of you to insult _our_ speaking of Prythan, a tongue that isn't our own, when it's clear that very few, if any, people in this room speak Scythian at all."

Keir gaped at her, an angry flush creeping up his neck. Cassian doubted any woman had ever spoken back to him like that - except perhaps his daughter. He likely wasn't used to it. He saw Rhys, in his place amongst the crowd, smirking at Feyre. Somehow she noticed it too, and twisted her head to raise an eyebrow at him.

"Prythan?" Keir sputtered, heedless of his High Lord's angry curses.

"What else should we call it? The common tongue? It's not exactly common in Scythia, is it?" Feyre countered. Her voice was acidic. "Don't be so ignorant or rude."

"My sister is right," Nesta said. "I hope most of you are more polite than him, or I would worry about the idea of a marriage alliance."

And Cassian wanted to grin as just like that, the woman asserted her dominance over the High Lord. She may just be a princess, an heiress, in comparison to him, but she knew he wanted this alliance, and considering she knew she was being betrothed to an illegitimate son, she likely knew why. She also knew she could easily seek a marriage alliance in any other court in Prythian, and she'd be well received. Threatening to do so only re-established what she'd likely known from birth: she had power. And she was cunning enough to know how to use it.

"We're sorry, Your Highness," the Lady of the Night Court said in response. "We've prepared rooms for you for your stay here; if you feel like it, you can retire there and join us for dinner later, or you could meet with Cassian now and get to know each other a bit."

 _Thanks, Stepmother_ , he wanted to drawl. He knew she was desperate - could hear the desperacy in her tone - but did she really have to throw him under the horse like that? He'd been doing very well at fading into the background, of the crowd and the conversation, and he didn't appreciate being dragged into the spotlight.

His anger dissipated though, at the pleading look she gave him even as she gestured with her hand. He sighed, and trudged forward.

"This is my son, Cassian," his father said, jumping in on the tactic his wife was using. It was perhaps the only time Cassian had ever heard his father admit they were related. "He's who we thought you might be interested in a marriage alliance with."

 _Don't you mean, he's who we're selling off like chattel?_ Cassian grumbled inwardly, but on the outside he tried for a bland smile.

Instantly, the eyes of both sisters moved to him. Feyre's looked slowly between him and Nesta, her face peculiarly intense. But Nesta Archeron herself, gaze blazing, simply looked him over once, face unmoving.

She muttered something to her sister, who replied in a light tone. Finally, Nesta said, "We want to go to our rooms, thank you."

Cassian didn't know whether to be relieved or insulted. His stepmother's face fell, but she murmured, "As you wish." The Crown Princess didn't so much as look at him when she left the room.

 **.~*~.~*~.~*~.**

 _"That_ _rude, uncultured piece of-"_

"And you tell me off for swearing," Feyre interrupted in a singsong voice, sitting on the bed next to her. "Don't descend to my level."

Nesta had clenched her fists, but they loosened at Feyre's joke. "You're right," she admitted. "Thanks for stopping me."

"No problem." Feyre began to ease off her shoes. She'd claimed that she didn't need to wear such fancy footwear, that the bejewelled pumps "gave her feet hell". But their mother had insisted, and their mother didn't insist on many things, so Feyre had swallowed her grumblings and agreed. "If Elain's not here to be the peacekeeper, someone has to step in. Oh, and also," she added, unstrapping her other shoe, "I'm still waiting for your apology."

" _Apology?_ What have I got to be sorry for? Not ordering the execution that awful man where he stood?"

"Saying that asking Alis to teach me Prythan was stupid and a waste of time. At least I didn't have to scrabble in hours and hours of lessons throughout a few months."

Nesta scowled. There were many bad things about her mother's hasty bid to arrange her marriage, and that was one of them: Having to cram as much time for language lessons into an already full schedule. "Alright, alright, I admit they may have been useful today."

"Thank you," Feyre stood up and flexed her feet. "But seriously, it's a shame you didn't order his execution. He seemed like a massive-"

" _Feyre_."

Her sister only grinned. The woman had spent an ungodly amount of time in her childhood running around the servants' quarters and the slums of the city, picking up bad manners and habits as she went. If Nesta was being honest, she liked her sister's accent; the speech pattern was familiar in the way that meant family, and the shamelessness with which her sister used it was one she envied.

Not that she'd ever admit to that, of course.

"But I have to agree. How dare he. _How dare he._ 'You speak with the intonation of the commoners.' Well, at least you speak it _at all_. He's not got much room to judge. The nerve of it all - and the way that man - Cassian - smirked at me - what is the world coming to-"

"Nes." Feyre interrupted again. She ruffled through her suitcase as she said, "You're starting to shout. The grooms in the stables can probably hear you. _Elain_ can probably hear you. I'll have Nuala and Cerridwen later, asking me what happened."

"You learnt the names of some of the servants already?"

"'Course."

Nesta pinched her lips together. She flopped back onto the bed in the sort of dramatic way Feyre had always said reminded her of the overzealous actors in the theatre. "How are you so calm about all of this?"

"We're in a court, Nesta," Feyre stated simply. It was the resignation to her voice that made her sit up and take notice more than anything else. "It's not even like the court at home, confined to the palace - this _entire territory_ is a court. The Night Court. And courts are full of gossiping hypocrites who'll kiss your ass if they think it will further their career and status, but turn on you the moment you fall from grace. I'm used to it by now."

 _But still hate it_ , Nesta finished silently. She didn't even reprimand her sister for the cussing. Of course, Feyre had more cause than anyone to know how harsh and judgemental a court can be. "How are you and Isaac, by the way?"

Her sister gave her a droll look from where she was still crouched on the floor. "Non-existent."

"Really?"

"Yup." Feyre rose, taking the jumper she'd been looking for with her. She came to lie on the bed next to Nesta. "We slept together maybe one or twice, but that was it. It was the rumours and shit that blew it out of proportion." As they did with every male Feyre had ever been seen with since she'd turned eighteen, whether she was with them sexually or not.

That was part of the reason it had been Nesta offered (against her will) into this marriage alliance, and not Feyre. The Queen had insisted her choice was due to "Feyre's maturity" and how she "doesn't need to rely on me to pick out a reliable partner for her" - not that Nesta had believed that in the slightest; their mother's flat out _callousness_ towards her youngest daughter's plight Nesta had seen when she sought out guidance to try to help her sister was sufficient to convince her that the Archeron matriarch (as one of Feyre's friends would say) didn't give a shit about the feelings of her own offspring.

No - she was just concerned that the rumours and reputation might end up spoiling the marriage.

Nesta had heard some of the words tossed around about Feyre. _Whore. Slut._ She'd tried to fight back, but it was a humbling experience indeed when the most powerful woman in the country realised she couldn't defend those she loved against her own people. Feyre, on the whole, bore it with her head held high.

"I don't think that man - Cassian - smirked at you," Feyre said idly. "He just sort of looked uncomfortable."

"Well, based on the smirk the Crown Prince was giving _you_ , excuse me if I make assumptions about the men here," she snapped, well aware she sounded haughty, and not caring either way. Feyre snorted. "Although considering that was directly after you explicitly insulted one whom I must assume is a powerful man, I supposed a smile that gleeful aimed at you could be excused."

"Always so fancy with your words." Feyre flicked her ear. For a moment, silence fell, before Feyre voiced a tentative question: "Do you miss home?"

She didn't know how to reply.

Nesta hated it here. She hated how alien it was, and though she had Feyre, she was in charge, and so was effectively alone. She hated that she didn't know what to do, that what was apparently an intelligent political decision earlier had been borne of anger in defence of her sister.

But this did not mean she missed home. "I suppose." Feyre hummed in response, and when Nesta looked at her, she had her eyes closed. "You?"

"Fuck yeah," her sister responded. Nesta laughed a little. "It's so cold, and I only brought one jumper."

"I'm sure we can buy some, or you can borrow some of mine."

"Sounds great." She hummed again, snatches of a lullaby Nesta had long since forgotten. "Oh, and Nesta?"

"Yeah, Feyre?"

"Don't be too hard on the bastard," her sister replied. "I know you hate it here, and you hate this whole idea, but it's not his fault. Do try to be fair to him."

"I'll do my best," Nesta deadpanned, and apparently that was enough, because her sister didn't press it any further.

 **.~*~.~*~.~*~.**

Princess Nesta was the star of the ball that night. Cassian's father had made him ask her to dance at least a dozen times by the time three hours had passed, and he was sure that by the umpteenth time, she was sick and tired of it. She certainly sounded like it.

"Stop standing on my toes, you brute!" She hissed. He'd found that whilst she was perfectly cordial, if a bit stiff, at the start of the evening, irritation had begun to set in soon enough and now he was intimately familiar with all her favourite insults and curse words. He stepped backwards unexpectedly, forcing her to move with him. She stumbled in her high heels, and nearly fell. "Ow!"

It said a lot that most of the insults she spat were in Scythian, and at one point, when she'd stalked off to get refreshments and he'd been forced to make small talk with her sister, he'd asked Feyre for a translation. She'd happily complied.

"You're a lovely woman, aren't you," he drawled close to her ear as they danced. She kicked him in the shins for the insult. "Ow! I'm just telling the truth!"

"You know, at this rate you'll end up without an engagement," she said, in much improved Prythan from earlier (he could only wonder how much she'd learned, just so she could rub it in their faces). He resented her for the fact that whilst it had been funny at the start, she never let anyone forget that she had the power in the situation, and she would wield it as she saw fit. "You're not being very impressive. And if I refuse, then where will you be?"

"Exactly where I was before," he said bluntly. He didn't care about manners at this point. "Exactly where I want to be. Hate to break it to you, Your Highness, but I'm not the one who wants this engagement. That's my darling father. He wants to build up ties with your country, and if that getting the bastard son he despises out of his sight, then whoop de doo, two birds with one stone."

He doubted that she understood most of what he was saying, but she got the general gist of it. She muttered something in Scythian. "I'm sorry, what was that?"

"I said I suppose that makes two of us!" She snapped. He was shocked into silence.

"Oh."

"Oh in-fucking-deed." She sneered. ('Fucking' was another word Feyre had translated for him; she claimed Nesta didn't swear often, so it was a real accomplishment for him to have push her to do so. She'd congratulated him for it. He'd found he liked Feyre.) "So maybe you should keep your mouth shut about things you don't understand."

"Maybe I should," he agreed as the song came to an end. "But you have to admit: If you're going to be shoved into an arranged marriage, at least one of the options is as pretty as me, right?"

She dropped his hands like they were red hot, and stalked off. He counted it as another victory.

He saw her around the party for the next few hours, talking to her sister, getting drinks, dancing with someone else, but he never went near her. Not until around midnight, when he approached the crowd that had gathered in the corner to watch whatever game had been set up in the corner. She was a part of the crowd, though he pointedly ignored her as he surveyed the table.

Chess. They were playing chess.

Of course. Rhysand loved that game.

And it was Rhys who was currently playing it, with a good few people surrounding them. Rhys's opponent was Tamlin, who looked like he'd lost quite a lot of games to the heir to the Night Court already, judging by his dark mood. Cassian knew exactly how much satisfaction his brother was getting out of wiping the floor with him.

Rhys still appeared to have most of his pieces, whilst Tamlin had a paltry three left. Rhys smugly picked up an ebony horse, and moved it to knock over the king. "Checkmate." Tamlin's face collapsed in horror as she stared at the board, and he snarled - actually snarled - at his opponent. "How many have I won now?" Rhys seemed to be enjoying this. "Seven? Eight?"

"Nine," someone in the crowd said. Cassian could see Rhys had known this perfectly well; he'd just been waiting for someone else to say it.

"Want to give up yet?" Rhys leaned back and smirked.

"This isn't finished, Rhysand!"

Tamlin erupted from his chair, almost overturning it, and stormed off. Cassian, watching him go, noticed him approach Feyre and try to make small talk; her disgust was obvious. Oddly enough, Rhys noticed this as well, and followed. The two chairs were left empty.

"Who wants to play next?" someone in the crowd asked, beginning to put the pieces back in their starting positions.

Cassian offered an, "I will," and sat in the chair. He wasn't as good as Rhys, but years of his brother needing someone to practice with had led to him getting pretty damn good at it. (Despite him losing every. Single. Time.) "Who want to challenge me?"

"I will." From the back of the crowd, Nesta Archeron came forwards.

He sighed. Of course. Of freaking course. "Are you sure you know how to play?"

She surveyed him coolly, and she'd never seemed more like a queen than when she did. "I'm certain." She sat down opposite him, her stare daring him to challenge her.

He did no such thing. "Alright then." He gestured to the board, the man having now put all the pieces back into place. "Shall we start?"

She nodded. He was on the side with the ivory pieces, so he moved first. He moved a pawn. She did the same. He moved another one. She did the same.

"Have you ever played chess before?" He asked her, grinning as one of her pawns came within reach, and he took it. "Just so I can know if I should go easy on you or not."

"Don't you dare go easy on me," she snapped in response. "And no, I've never played it before, but I think I've managed to observe enough tonight to guess how to play." He grinned, and moved his bishop three spaces directly forward. She sniffed. "That piece can only travel diagonally, and you know it, Cassian."

His grin dropped, and he moved it back to its original position, moving another piece instead. "No need to be so passive aggressive about it, Nes."

Her eyes flashed, and she made a move without thinking about it. "Don't call me that."

He took the piece she'd led into danger. "My apologies, Nes," he smirked. She narrowed her eyes. "Is it too intimate for you?" Her lips peeled back from her teeth, and for a moment he could only look at them, and wonder if they were as soft as they looked, how they would feel if he. . .

He looked back down to find she'd taken the piece he'd moved to take hers, and that in his state of distraction he'd moved another piece into danger. She snapped that one up quickly as well.

"Perhaps - if you don't want to lose, that is - you should focus on the game, and not my breasts." She commented cockily. He growled in response. He hadn't been looking at them, but he was now that she'd mentioned them, and- _She'd taken another one of his pieces Cauldron damn it_.

He glared at her. She gave him a sweet smile in return. "Something wrong?"

Bitch. Clever, clever bitch. Feyre had walked over now, closely followed by Rhys. The princess looked just as amused as her sister, and once he realised what Nesta was doing, Rhys did as well. Some brother that one was. Cassian's list of people he disliked was growing longer by the minute.

But, focusing back on the board, he realised she'd made a fatal mistake in her confidence. He moved his bishop right up beside her king. "Check," he said gleefully.

Nesta frowned as she looked at the board. Triumph surged in his gut. Then she smiled. She moved her queen, very pointedly knocking over a piece as she did.

It rolled off the table. Each and every bounce of the carving against the marble floor was damningly loud. He didn't want to look to see which piece it was. But he steeled himself, and he did. His heart sank.

It was the king.

"Checkmate."

"How-" He gave up the question halfway through as he looked at the board. He could see how: In his eagerness to win, he'd moved the only piece standing between his king and her queen and left the gap wide open. He could see Rhys in his peripheral vision, folding his arms, shaking his head and chuckling. It was a mistake he'd always thought himself above making.

Nesta was something, wasn't she?

What she was, exactly, eluded him, but she was definitely something.

And one day, she'd definitely be _someone._

Both the Archeron sisters would.

"Play again?" He offered. Nesta's face cracked into something he hadn't seen on her yet: a full blown smile.

"Alright."

Yes, she would definitely be someone. And Cassian decided then and there that he wanted to be there to see who.

* * *

 **What did you think?**


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